This protocol is a component of the Columbia Center for Children's Environmental Health research program, funded by NIEHS and the U.S. Environmental Protection Agency. The goals of the prospective cohort study of 400 African American and Dominican women and their newborn infants are to: 1) assess the effects of prenatal exposure to polycyclic aromatic hydrocarbons (PAH) and environmental tobacco smoke (ETS) on fetal growth and childhood growth and neurocognitive development; 2) assess whether prenatal and/or postnatal exposure to home allergens and ETS, as well as postnatal exposure to PM2.5 and diesel exhaust particulates (DEP) are significant contributors to risk of asthma; 3) evaluate whether impaired nutritional status and community-level stress factors related to poverty heighten susceptibility to these environmental pollutants; and 4) carrying out a series of intervention projects to reduce risks of asthma and poor birth outcomes. Over the course of this four-year study, a total of 400 women who have registered at the OB/GYN clinics at Harlem Hospital Center and CPMC will be enrolled. Because an important aim of the study is to explore the contribution of air pollution to adducts and health outcomes, the study population is restricted to women who have resided in the area for at least one year. Current smokers are also excluded because smoking may confound the association between ambient PAH exposure and fetal development. Each subject is monitored for two days around the 30th week of pregnancy. A sample of infant cord blood is collected at delivery, and a sample of maternal blood is obtained at 1 to 2 days postpartum. When the infant is 6 months and 12 months old, follow-up assessments, including measurement of infant weight, length and head circumference, and administration of the Denver Development Test are undertaken at the GCRC.